c# - 在这个带有连接的 LINQ 查询中使用 Min 和 Max 函数？

Question

我正在做一个 LINQ 查询，它是多个表的连接。在结果集中，我想在表格中添加一个同时显示最小和最大日期的列[例如（20/3/2012 - 25/4/2012）]。

我想从中选择日期的表（这是一个管理多对多关系的表）的结构如下：

BookedAreaID    int
AreaID  int
LeasedDate  datetime
InvoiceID   int

这是我的 LINQ 查询：

var selectedResults=
from InvoiceSet in Invoices
join BookedAreaSet in BookedAreas on InvoiceSet.InvoiceID equals BookedAreaSet.InvoiceID
join AreaSet in Areas on BookedAreaSet.AreaID equals AreaSet.AreaID
join ContactSet in Contacts on InvoiceSet.ContactID equals ContactSet.ContactID
join Contacts_ObjectsSet in Contacts_Objects on ContactSet.ContactID  equals Contacts_ObjectsSet.ContactID
join CompanySet in Companies on Contacts_ObjectsSet.ObjectReferenceID  equals  CompanySet.CompanyID
join BookedAreasSet in BookedAreas on InvoiceSet.InvoiceID equals BookedAreasSet.InvoiceID

where Contacts_ObjectsSet.ObjectReference=="Company"

select new {InvoiceSet.InvoiceNumber,InvoiceSet.Amount,InvoiceSet.TotalDiscount,InvoiceSet.GST,
InvoiceSet.PaymentDate,InvoiceSet.ShoppingCentreID,BookedAreasSet.BookedAreaID,AreaSet.Name,Paid=(InvoiceSet.PaymentDate==null ? "UnPaid":"Paid"), 
licensee=(CompanySet.CompanyName))
};

我想用这个查询选择类似的东西：

DateRange=
(Min(BookedAreasSet.LeasedDate where BookedAreasSet.InvoiceID=InvoiceSet.InvoiceID) 
+ "-" + 
Max(BookedAreasSet.LeasedDate where BookedAreasSet.InvoiceID=InvoiceSet.InvoiceID)

Answer 1

好像你在这种情况下加入了两次顺便说一句：

“在 InvoiceSet 上的 BookedAreas 中加入 BookedAreasSet。InvoiceID 等于 BookedAreasSet.InvoiceID”

不能随便用吗？

DateRange=
(Min(BookedAreasSet.LeasedDate) 
+ "-" + 
Max(BookedAreasSet.LeasedDate))